臭氧去除Diclofenac及其中間產物、副產物生成之研究

Formation of the intermediates and by-products during the degradation of diclofenac by ozonation

胡乃心(Nai-Hsin Hu)

指導教授 ： 蔣本基

共同指導教授 ： 張怡怡(E-E Chang)

國立臺灣大學/工學院/環境工程學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.02091

摘要

雙氯芬酸 (Diclofenac )為一種非常廣泛使用的非類固醇抗發炎藥物，目前已有許多文獻證明在不同的生物體以及環境中，雙氯芬酸可能造成的危害影響以及濃度。許多研究調查指出，雙氯芬酸不能完全藉由傳統的汙水處理廠去除，並可被許多污水處理廠檢測出微量濃度，且進而進入自然水體之中。因此，評估雙氯芬酸存在環境水體之問題應被重視。
本研究目的在於評估臭氧處理程序對雙氯芬酸去除的影響。評估不同的操作條件，例如：臭氧劑量、pH、及磷酸緩衝溶液的添加對雙氯芬酸以及總有機碳去除影響之調查。更進一步利用測量氯離子、銨根離子、中間產物與臭氧副產物的生成潛勢，加上對元素碳、氯、以及氮的植量平衡，發展雙氯芬酸降解預測模式，可決定反應動力常數與解釋雙氯芬酸降解機制，以及決定實驗對去除水中的雙氯芬酸的最佳化操作條件與參數。
研究結果顯示出，利用臭氧處理程序可有效的去除雙氯芬酸。在不添加磷酸緩衝液，使溶液的pH值呈現變動的狀態下，雙氯芬酸和總有機碳的去除效率大致會因臭氧劑量增加而增加，而臭氧無機副產物形成率，如氯離子以及銨根離子，會與臭氧劑量無顯著的關係。另外，在添加磷酸鹽緩衝液，固定溶液的pH值於5.5、7.4、和8.9下，最大雙氯芬酸的消耗反應速率常數，和二氧化碳形成反應速率長數，在兩個不同臭氧劑量下，均在pH 7.4時得到最大值。雙氯芬酸的反應速率常數可藉由假一階以及推測的二階反應求得，而預測模型可以計算出反應途徑的選擇性。此外，研究指出，在紫外光處理程序中，臭氧副產物醛類生成濃度隨操作條件pH增加而增加生成量，主要原因為較有多氫氧自由基，容易將有機物質氧化成小分子醛類物質。最後利用考慮副產物生成速率、雙氯芬酸降解速率，以及健康風險的數值可評估雙氯芬酸降解的最佳操作條件與參數。

關鍵字

雙氯芬酸 ； 臭氧 ； 臭氧副產物 ； 反應速率常數 ； 動力模式

並列摘要

Diclofenac (DFC) is a widely used anti-inflammatory drug and thus enters the aquatic environment. The realistic environmental concentration levels at harmful effects to different organisms have been demonstrated by many previous studies. Many investigations have revealed that diclofenac can not be completely removed by conventional sewage treatment plants (STP) and was detected in STP effluents at trace levels. Therefore, the presence of diclofenac in the aquatic environment should be assessed critically.
The objective of this study was to evaluate the removal of diclofenac using ozonation process. The effect of various operating parameters including ozone dose, pH, and the presence of phosphate buffer on the removal of diclofenac and TOC in ozonation process was investigated. In addition, the formation of ozonation by-products, including chloride, ammonia ions, intermediates and aldehyde, was also studied. Meanwhile, a simplified mass balance based on intermediates containing carbon, chlorine, and nitrogen was developed to determine the formation rate constants of CO2, chloride, and ammonia. Furthermore, kinetic studies based on the degradation of diclofenac and formation of chloride and ammonia were also developed to determine the selectivity of reaction pathway and rate constants of diclofenac. Finally, the constants obtained in this study were used to propose the possible pathway and evaluate the optimum operational parameters.
The results show that ozonation was efficient in degrading diclofenac. In absence of phosphate buffer, the removal of diclofenac and TOC, and formation rate of chloride basically increased as the ozone doses increased. In presence of phosphate buffer, the maximal diclofenac removal and CO2 formation rate constant is at pH 7.4 at two levels of ozone dose. The reaction rate constants of DFC can be determined in a second order reaction. The diclofenac degradation models can predict the selectivity of pathway. In addition, the aldehyde concentration increased with increasing pH in the ozonation process, which indicated the involvement of hydroxyl radical in aldehyde formation.

並列關鍵字

Diclofenac ； Ozonation ； Ozonation by-product ； Kinetic constants ； Intermediates ； Pathway ； Optimum operational condition

參考文獻

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